Device for determining the direction of flow of a magnetic field



March `1 7, 1931. w. A. Low-l 1,796,295

nsvzcf: Foa mz'rsnmrmue THE DIRECTION cr FLow or A manana HBL'D FiledMarch 23, 1923 2 Sheets-Sheet 1 Much 17, 1931. w. A. LcTH 1,795,295

DEVICE FOR DETERHINING THE DIRECTION OFI1 OW OF A MAGNETIC FIELD Fileduarh 2'3, 192s 2 sheets-#sheet 2 Fig-4 i l 25'/ Patented Mar. 17, 1931Ygg 11;.' E

WILLIAM ARTHUR IAOTH, 0F PARIS, FRANCE, ASSIGNOR T0 SOCIT INDUSTRILLEDES PROCEDES W. A. LOTH, 0F PARIS, FRANCE DEVICE FOR DETERMINNG TI-IEDIRECTION OF FLOW 0F A MAGNETIC FIELD Application led March 23, 1923,Serial No. 627,224, and in France March 18, 1922.

Application filed in France March 18, 1922, Patent No. 549,095.

The present invention has for its object a device for exactlydetermining the direction 5 of the magnetic or electromagnetic fields oflow, medium or high frequency. It comprises windings preferably radiallyarranged about a com-mon axis and connected in series; the currentsinduced in these windings by an 10 external magnetic orvelectroniagnetic field being collected by means of a commutator, whichis provided with two rotating brushes diametrically arranged oppositeeach other and electrically connected together by means of a receivingapparatus, such as an amplifier and telephone.

In the accompanying drawings and by way of example:

Fig. l is a diagram showing the radially arranged windings.

Figs. 2 and 3 illustrate two forms of construction ofthe device inaccordance with the invention.

Fig. 4 shows a form of construction of the armature.

Figs. 5 and 6 are end views of two constructional modifications of thecommutators combining with the windings of the armatures.

The drawing shows the use of a winding in the shape of a ring, on avertical cylinder l (nonmagnetic for instance), having a permeabilityequal to that of the air. The winding is constituted by an insulatedconductor 2 wound according to the radii of the base circles and thegeneratrices of the hollow or solid cylinder l, made of wood forinstance. These turns form a circuit completely closed on itself, eitherdirectly or through the medium of a device for putting it in resonance.For collecting the induced current generated in this winding 2 by thevariations of the magnetic flux 3 passing through these turns, use ismade (Fig. 2) of a switch rotating about an axis 7 and carrying at theend of its arms brushes 72 electrically insulated relatively to eachother. These brushes 7 2-rub on a resistance, which is either a purelyohmic resistance 7l as shown in Fig. 2, or an inductive resistance 7 3as shown in Fig. 3.

Wires connect equidistant points of the resistance 71 or 7 3 toequidistant points of the winding 2. i

To the two brushes 72 can be connected telephones or any currentdetectors, either directly-or through the medium of amplifiers tuned ornot. The apparatuses may also, instead of being directly connected to.

the brushes 72, be connected thereto through the medium of one or moretransformers, this allowing to put again the secondary circuitV vit willbe seen that the elementary currents induced in each turn or each groupof turns of the winding vary from one to the other and are then afunction of the inclination of these turns on the direction of the lluX.Thus the current induced in the turns the planes of which are parallelto the direction of the magnetic flux, low frequency (turns 16) is null.since no line of force of the eld 3 passes through their surface.Conversely, the maximum currents are induced in the coils 17, the planesof which are at right angle to the lines of force of the magnetic field3. Therefore, the elementary currents induced in each turn depend on thelocation of this turn relatively to the flux and vary from one to theother, but the total current collected by the brushes, current whichimpresses the receiving apparatus is, for a position of the brushesrelatively to a flux, the sum o f these elementary induced currentswhich are unequal, and, for all theother positions of the brushesrelatively to the liuX, is the result, characteristic for each position,of a differential reception of the two halves of the winding. It will benoted that in the particular case ofthe winding passing again throughthe center, there are tively to the center, which occupy positions equalin inclination and approximately equivalent in distance, relatively tothe linx.

The currents induced in these turns or coils are therefore veryapproximately equal. ln the case of the winding passing around the druml according to the successive diameters, by turning about the center,each turn or each coil occupies, on the contrary, a different positioncharacteristic, relatively to Vthe flux and each elementary inducedcurrent has a characteristic 'value' diiferent of that of the currentinduced in the other turn or coil nearest to the right or to the left.

It will be noted rthat these elementary induced unequal currents from aturn (or coil) to the following one, are added to each other for eachhalf of the winding taken on one side of the magnetic i'iux (Fig. l) andthat their sum is opposed to the equal sum of the elementary inducedcurrents, unequal to each other, of the other halfl of the winding,symmetrical to the first half relatively to the direction of the flux.The resulting induced current is therefore, as above stated, null in theinduced winding closed on itself. V lf by means of a conductor externalto theV winding, the connection is effected of points (two for instance)of this latter (and, for.

example, two diametrically opposed points), the current circulating inthis conductor, on which can be directly .or indirectly branched currentdetectors, will therefore be function of the position of the brushesrelatively'to the direction of the flux generated by the eX- ternalfield and, as stated, characteristic of this position. Y

lt is possible to use two points of contact for instance. lf these twopoints of contact are vplaced according to the direction of the magneticflux 3 of a frequency of 600 periods per second, it will be seen thatthe resulting current will be maximum.

@n the contrary, it will be seen that ifione Y connects by means of anexternal circuit, diametrically opposed points which are placed at rightangles to the direction of the magnetic nur, no current will passthrough the receiving apparatus, each quarter of the winding beingcompensated by the quarter, equivalent in position relatively to themagnetic flux 3 and belonging to the other half of the armature; A Theturns, frames or elementary Vwindings O nected 'either in parallel, orby series-groups connected in parallel. V'lhese turns, frames orwindings can also constitute independent windings the connection ofwhich about a comin-on directing axis lictiously represents theformer-solid of the said windings. The connections between thesewindings are then so devised that the latter are connected in parallel.

.u constituting the armature can also be con-l The current produced inthe windings 2 of the armature can be collected in various manners. Byway of example there will be described hereafter two particular meansapplying one to the case in which the receiver is itself in parallelwith the windings 2 of the armature (the coinniutator being very or notvery resisting according to the nature of the receiver) the other, incase the kreceiver is connccted in series with the circuit of thewindings 2 of the armature.

t relates to the first of these means; only three groups of two turnshave been shown for each elementary armature winding instead of a (acan, for instance, be equal to eee, iso or so). Y

The ends Ell of the conducting turns Qar'e connected to a collectingring 35, of known resistance'. rlhe opposite ends 36 of these turnsV 2are connected to a second conducting ring Si.. rlhe brushes 4L,insulated from each other, allow of collecting the current produced inthese turns 2 by a variable magnetic or electromagnetic field, of anyfrequency. Between the n' fi is branched `the receiver 2l of electric curent, either directly in a circuit *f d or not or indirectly, withcircuit tuned or not, throu the medium of an amplifier 29. ylhesearrangements allow of receiving by any of the methods used in Vhigh orlow frequency, either for telegraphic or telephonie applications, or forall the other applications, such ,as the guiding of ships and airplanes;Y ifil conducting bar 88 can be added to the said arrangements, this barmoving on .the commutator 37 together with the brushes 3;

in combination with that numbered 21 which is inserted between thebrushes 4, or independently of the receiver 2l. rl`h'e brushesli rubbingon the conducting ring of .the .commutator can be arranged in alignmentwith each other or theyV can form an angle of 90 1 if two receivers areused'as previously indi- Vthe saidbar is :madeV in one piece or intliisf bar is inserted a second receiver acting either iio desirablecombinations can then be effected between these two induced receivedcurrents,

either by adding theni or by opposing them.k

it is also possible to eifect the saine combi nation of brushes aand 38angularly. arranged on the rings 35 and on the rings 37.

Fig. 5 illustrates, in plan view, the armature and shows moreparticularly the coinmutator 35 constituted by turns ofbare re-.

sisting wire, corresponding to the resisting ring 35 (Fig. 15'). lf itis admitted that the fluir follows the direction of the arrow a, it willbe seen that the induced currents will follow the directions 39 towards40 and 39 towards 4l in the commutator. If the brushes are placed asshown in the line 40e-4l, they will receive at the maximum. A kind ofWheatstone bridge is thus obtained the effect of which will be increasedowing to the arrangements of a second pair of brushes 38 moving on thesecond collecting ring 37; these brushes are either directly andmetallically connected, or are connected to each other at the terminalsof a receiver.

It is obvious that in the case of turns in parallel as well as in thecase of turns in series, the direction of the flux could also beobtained by causing the whole of the induced receiver torotate about itsaxis; but it is preferable to keep this fixed armature and to operate asdescribed.

In the form of construction shown in Fig. 6, the ends of the conductingturns 2 are connected to contact-pieces 10 insulated from each other. Inthe figure, for the clearness of the drawing, 2O turns only have beenshown. 'Ihe opposite ends of these turns are connected together by aconducting ring similar to the ring 37 and forming a. commutator, or arealso connected t0 contact-pieces insulated from each other on which canbear and rotate a metallic ring cut at two points and in which arearranged two transformers or less. In the latter case, the operation ofthe commutator connected in parallel to the ends of the turns 2 issimilar to that of the comniu-tator connecting their other ends.

On the contact pieces of one or the other commutator rests a collectingring 5 6 which can slide on the same by rotating about an axis passingthrough the center of the system. This ring 5 6 is cut at two points43-44 as shown for instance in Fig. 17. These gaps are constituted byinsulating surfaces. The terminals of the primary 45 of the transformeror those of a receiver are connected either directly or indirectly tothe ends of the first break or gap 43, the ends of another primary 46 orof another receiver are connected to the ends of the second break orgap. In the diagram of installation shown in Fig. 17, the ends of thebreak or gap 43 on the one hand and the ends of the break or gap 44 onthe other hand, are connected to the terminals of the two primarywindings 45-*46 of one and the same (or of two) transformer, the commonsecondary 47 of which or the separated secondaries) are in tunedcircuit, either directly or through the medium of an amplifier 29, withthe receivers 2l or current detectors.

If it is admitted that the direction of the liux is that indicated bythe arrow a, it will be seen that if the movable commutator 56 withdouble break 43-44 (which can slide on the contact pieces 6 in thedirections indicated by the arrows ZJ) occupy such a position that thesebreaks 43-44 are arranged on the straight line 40-41, the currentsinduced in the turns by the flux then circulate in the direction of thearrows 48, and the windings of the transformers will be traversed bymaximum and equal induced currents. 0n the contrary, if the position ofthe collecting ring 5-6 on the contact pieces l0 is such that the breaks43 and 44 are arranged on the line 39--42, the transformers will betraversed by a minimum current which can even become null. From theposition of the brakes 43-44 on ythe graduated circle (in degrees forinstance) at the time of the maximum or minimum reception, it ispossible to determine the direction of the field. The direction of thefiux can obviously be determined by a compared reception of the twoprimaries of the transformer placed at the breaks L43--44 It is obviousthat instead of two breaks as shown, it is possible to use a conductingring presenting a greater number of breaks and such for instance as fourbreaks arranged at 90 from each other.

As shown in Fig. 2, the resistance 71 is set in position relatively tothe winding 2 so that the tappings on the two apparatuses occupyidentical respective positions. If this condition is not carried out, itwill be convenient to angularly move the resistance 7l so as to causethe minimum observed by it to coincide with the parallel orperpendicular to the direction of the magnetic or electromagneticinducing iield.

On the resistance rub two conducting brushes 7 2 insulated from eachother and arranged diametrically opposite to each other. Each of them isin relation with a terminal of the receiving circuit. These brushes canthus respectively rub on fixed metallic crowns in relation with thereceiving circuit. It is seen that the distribution of the inducedcurrents in the turns of the winding 2 are reproduced at a distance inthe turns of the rheostat 7l.

Two characteristic positions are thus obtained, one of which gives amaximum, the other a minimum current in the receivers and this in a veryprecise manner. For intermediate positions one has currents ofcorresponding values intermediate between the maximum and the minimum.Instead of two brushes, a greater number of brushes symmetricallyarranged can be used.

This resistance can obviously have any winding, inductive or not and ifit is wound on a core, this core may be metallic or not, laminated ornot, etc. It is obvious that the various commutators described can becombined together, onthe armature or at a distance.

It is obvious that, instead of the resistance, a small inductive windingmight be used, constructed for instance as previously described for thewinding 2. In this case, the conductors starting from the tappings oncontact brush, for instance.

the invention are` the turns of the receiving winding 2 similarlyvleading toA the corresponding turns of thev inductive winding 73 onwhich the current is taken directly or indirectly by means of a If theapplications of now considered, the following remarks may be made:

In case of electromagnetic guiding for instance, or in case of wirelesstelegraphy, itis known that on board certain movableobjects (airplanesor ships), the reception can be hindered by local parasites arising fromelectric apparatuses (magnetos, dynamos, etc.) It is known that theseyeffects can be compensated by means of a small frame placed near theproducers of parasites. It is obvious that, in this case, the smallframes can be replaced by small windings according to the invention,provided with a commutator and placed above or at a distance. Thesesmall compensating windings arethen directly or indirectly connected tothe large frames or to the large receiving windings.

Moreover, it is to be noted that, whenthe guiding of ships is effected,use is made, in combination with vertical frames, of two horizontalframes laterally arranged on either side of the axis of longitudinalsymmetry of the movable object. frames may also be replaced by windingssimilarly arranged. The commutators can also be placed relatively toeach of the windings in the position most favourable for the comparisonof the intensities. These arrangements permit, at every moment,todetermine the inclination of the lines of force of the magnetic fieldpassing through each winding. As on the other'hand, the shape of thefield is known, it is therefore possible, for one and the saine knownheight of the bottom, to determine the distance from the movable objectto the emitting cable-function of the inclination of the lines of force.This method is safer and more sensitive than that permitting todetermine the distance by evaluation of the variation of the inensity ofreception. Y

l/Vhat I claim as my invention and desire to secure by Letters Pate-ntis:

1. In an apparatus for exactly determining the direction ofelectromagnetic fields, a closed winding formed by a plurality of turnsof conductors arranged angularly relatively to each other and connectedin series, aY

resistance arranged circularly, conductors connecting points of saidcircular resistance to corresponding points of the closed winding, andbrushes provided for effecting a con` tact with said resistance andarranged Vin a receiver circuit.

2. In an apparatus for exactly determining the direction ofelectromagnetic fields, a

closed winding determining a body of revolution formed by a plurality ofturns or conn The side ductors `arranged angularly relativelyl to eachother and connected in series, a resist-v ance arranged circularly,conductors connecting points of saidresistance topcorresponding pointslof the closed winding, and two diametrically opposite brushes providedto effect a contact with saidcircular resistance.

posite turns of said winding in parallel with'V the receiver circuit.

In testimony whereof I have signed my naine to this specification.

lWILIiIilvI ARTHUR VLOTII.

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